The present invention relates to the monitoring of vehicular traffic flow in a road network, and more particularly to the generation of traffic congestion reports.
With ever increasing road traffic levels there is a particular need for the rapid generation of traffic congestion reports in order to enable a rapid response thereto such as action to remove the cause of traffic congestion, and avoiding action by road users approaching an area of traffic congestion.
Existing methods generally depend on physical detection of the vehicles by direct visual observation or by using various kinds of sensors such as cameras or proximity sensors embedded in the roadway etc. The former approach can provide only extremely limited coverage due to the large number of personnel required, while the latter requires the installation in the road network of a very extensive and expensive infrastructure.
It is an object of the present invention to avoid or minimise one or more of the above problems or disadvantages.
The present invention provides a vehicular traffic flow monitoring method for monitoring vehicular traffic flow in a road network in an area served by a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system providing positional data in respect of at least active mobile telecommunications devices belonging to said mobile telecommunications device network, said method comprising the steps of:
a. capturing first geographical positional data for an active mobile telecommunications device in use on a vehicle at a given time t1;
b. intersecting said first geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify original possible road components corresponding to said first geographical positional data;
c. generating an initial probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said original possible road components for all of said original possible road components;
d. capturing second geographical positional data for said mobile telecommunications device at a later time t2=t1+xcex94t where xcex94t is the actual transit time of said device between said first and second geographical positions;
e. intersecting said second geographical positional data with said road network mapping data, so as to identify new possible road components corresponding to said second geographical positional data;
f. identifying available routes in the road network linking said possible road components corresponding to said first and second geographical positional data which routes are constituted by a series of road components;
g. generating an updated probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said new possible road components in the road network corresponding to said second geographical positional data at said later time t2 via one of said available routes, for all of said new possible road components;
h. intersecting said available routes with expected average vehicle speed data for the road components of each of said series of road components constituting said available routes so as to determine expected transit times for said available routes;
i. directly or indirectly comparing the actual transit time with the expected transit times for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time; and
j. determining an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of any of the available routes having been followed.
In another aspect the present invention provides a vehicular traffic monitoring system suitable for use in the method of the present invention and comprising a computer system having:
a storage device; a processor connected to the storage device; and at least one interface connected to the processor, the storage device storing digital mapping information for a road network, expected vehicle speed for road components of said road network, and a database of at least: probability vectors representing the likely positions of moving active mobile telecommunications devices over a period of time and the likely routes thereof to said likely positions, and current road delay factor information;
said at least one interface coupling said processor to a mobile telecommunications device network call management system for interrogating said management system and receiving positioning data for active individual mobile telecommunications device therefrom; and
coupling said processor to user enquiry systems for receiving road traffic delay enquiries from, and transmitting road traffic delay reports to, said user enquiry systems; and the processor operative with the program to:
a) capture geographical positional data for a mobile telecommunications device;
b) intersect said geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify possible road components corresponding to said geographical positional data;
c) generate a probability vector representing the likelihood of said vehicle having arrived at a position on any of said possible road components;
d) identify available routes in the road network linking said possible road components corresponding to a given geographical positional data and preceding possible road component corresponding to a preceding geographical positional data, which routes are constituted by a series of road components;
e) intersect said available routes with expected average vehicle speed data for the road components of said series of road components constituting said available routes so as to determine expected transit times for said available routes;
f) directly or indirectly compare the actual transit time with the expected transit time for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road component thereof at the time;
g) determine an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of a given available route having been followed;
h) repeatedly update said database of moving active mobile telecommunication devices and road components with vehicle position and road delay factor information; and
i) retrieve road delay factor information from said database in response to enquiries from user enquiry systems and provide road delay factor reports thereto.
Thus by means of the present invention it is possible to provide road traffic delay reports for a road network, which are substantially live i.e. based on historical road traffic flows immediately before the reports are generated, using only suitably programmed data processing equipment connected to a mobile telecommunications device network, without the need for providing the road network with any new infrastructure.
As used herein, the expression mobile telecommunications device network indicates any telecommunications device system in which a multiplicity of mobile subscribers (MS) with mobile telecommunications devices (which may be conveniently referred to herein for brevity as MS devices) can communicate with each other and/or fixed-line subscribers via one or more transmitter/receiver stations which may be terrestrial and/or extra-terrestrial.
It will be appreciated that the present invention requires to discriminate not only between mobile telecommunications devices located in or on road vehicles and those located inside buildings or being carried be pedestrians etc., but also between those carried by vehicles travelling along the road network which might at times be temporarily stationary e.g. at traffic lights and those carried in vehicles which are parked and not travelling at the time. This may be achieved by a number of different positioning system technologies which are available for generating geographical positional data or proto-geographical positional data for individual mobile telecommunications devices when they are active i.e. involved in sending and/or receiving data or voice messages. It will be appreciated that different positioning technologies may be used with different types of network. One widely used mobile telephone system is GSM (Global System for Mobile Communication) which is a global standard and is currently deployed by over 300 operators in over 140 countries world-wide. GSM is deployed in the UK by Vodafone, Orange, BT Cellnet and One-2-One and in the USA by various companies including Omnipoint, Sprint and Airtouch. The next generation digital mobile standard (UMTS) is in fact also based on some aspects of GSM and thus similar location technologies to those used with GSM will also be usable with UMTS. The principal positioning technologies available for mobile subscriber device location include the following:
CGI+TA (Cell Global Identity+Timing Advance). This method can determine the distance of an active MS device (i.e. one actively engaged in a telecommunications transmission) from a particular transmitter/receiver base station to an accuracy typically of the order of 550 m (within an annular zone (complete 360xc2x0 arc) around the base station which has a radial depth of 550 m). The information can also be ascertained by xe2x80x9cpagingxe2x80x9d an xe2x80x9cidlexe2x80x9d MS device (i.e. one which is switched on but not actively engaged in a call). This method requires no MS device modifications. A base station with multiple directional antennae (which are now common) reduces the location arc to a sector around the base station of, for example, 120xc2x0. Further enhancements are planned to increase the accuracy of this method to between 100 m and 200 m.
It should be noted here that with some kinds of network, for example GPRS (General Packet Radio System) networks, an MS device which is switched on but not actually involved in sending any communication to or from the MS, is still in communication (at least periodically) with the call management system for the purposes of managing the network, and accordingly references to xe2x80x9cactivexe2x80x9d MS devices in the context of the broadest scope of the present invention, should be interpreted as including devices in any kind of communication with the call management system.
UL-TOA (Uplink Time-of-Arrival). UL-TOA can determine the location to within 50 m to 150 m, depending upon terrain, by measuring the time taken by the signal from the mobile handset to arrive at multiple xe2x80x9cmeasurement pointsxe2x80x9d. In more detail distances from each of these different measurement points is determined from the respective times which can be used to determine the position of the MS device by triangulation.
E-OTD (Enhanced Observed Time Difference). Unlike CGI+TA and UL-TOA, this method places the responsibility for determining location in the MS device, and hence incurs little extra expense for the mobile operator. Essentially this method is the reverse implementation of UL-TOA. The accuracy is similar to that of UL-TOA (about 60 m in rural areas and 200 m in bad urban areas).
A-GPS (Assisted Global Positioning System). GPS is commonly used for navigation systems in cars. GPS technology relies on a network of satellites orbiting the earth and transmitting signals which a receiver unit on the ground can use to calculate its own location. The GSM network can provide assistance that gives increased accuracy over standalone GPS systems by making use of the actual precisely known position of the base stations and comparing these with the base stations as reported by the GPS system in order to generate a correction factor which can be applied to the mobile subscriber device position as reported by the GPS system. The accuracy of this method is extremely high but requires modifications to mobile handsets.
The particular positioning or location method technology used is in many respects unimportant to the implementation of the traffic congestion reporting system of the invention. The common attribute all these methods share is that the location position for each MS may be expressed as being within a given area of uncertainty in whatever form of coordinates etc in which this is expressed. It is the responsibility of the system of the invention to xe2x80x9cfitxe2x80x9d a series of such readings onto a physical road traffic network and identify those readings which are likely to be in moving vehicles. The mobile telecommunications device network equipment vendors (alongside third party companies) are developing various mobile positioning solutions based on one or more of the above technologies. Most of these companies offer proprietary interfaces but there is an ongoing effort to standardise location or position based services and it is anticipated that this interface will be widely supported. The Ericsson Mobile Positioning Protocol (MPP) has been selected as the basis for the standardisation. This provides an interface with which to query the Ericsson (or other compatible) Mobile Positioning Centre (MPC) in order to extract positioning data for individual MS devices. The MPP hides the particular mechanism which is used by the MPC to locate the MS device which therefore could be based on any of the aforementioned technologies.
The size and form of the area of uncertainty defined by the positioning system or MPC will vary according to the particular positioning system used. In the case of a CGI-TA based MPC individual terrestial mobile telecommunications device network transmitter/receiver stations (including repeater stations) each serve a sector-shaped area radiating out from the station, where the angular spread of the sector may be 360xc2x0 or any smaller angle, such as for example 120xc2x0. The sector may extend several kilometres or more in any given direction depending on the topography of the area around the station. Due to the increased delay experienced in transmission of signals between a station and a MS device as the distance of the MS device from the station increases, the sectors are divided up into a series of annular timing advance zones so that as a MS device moves away from the station, it passes from one timing advance zone to a neighbouring one in which signals are subjected to a different timing correction so that these delays can be compensated for and the signals from various MS devices at different distances from the station are all properly synchronised. Typically the radial extent of each zone is several hundred meters, for example, about 500 meters. At the boundary between adjacent zones (the timing advance boundary) there is generally a small overlap or intersection region which may have a radial extent of the order of 50 to 100 meters. It will of course be appreciated that a vehicle travelling along a road will at some stage also cross over from a timing advance zone of one station into a timing advance zone of a neighbouring station and such transitions are also used in essentially the same way in the method of the invention.
For the purposes of management of calls within the mobile telecommunications device network, the positioning information can simply comprise the identity of an individual base station cell (the geographical area served by an individual base station), and the particular timing advance zone of that cell, within which the MS device is located. Insofar as such positioning information is not in a form which defines geographical position as such in conventional terms such as longitude and latitude or other suitable co-ordinates, but can nevertheless be readily converted into such a form from a knowledge of the actual geographical positional data corresponding to the particular timing advance zone, such positioning information may conveniently be referred to as proto-geographical positional data. The conversion of such proto-geographical positional data into geographical positional data could be carried out by means of suitable additional processing at the positioning system, or alternatively at a computer system of the present invention which is disposed separately or remotely from the positioning system.
The road network data used in the method of the present invention is generally in the form of a data file which can be more or less easily operated on mathematically. One convenient readily available and adaptable data file format is GDF (Geographic Data File) in which road networks are stored in the form of nodes representing junctions and edges representing each carriageway or road direction between neighbouring junctions. This particular data file format has the advantage that it can include information on the classification of roads i.e. distinguishing between motorways and other major or trunk roads and minor roads, which can be used as a basis for weighting such roads when constructing a probability vector for a vehicle on the basis that there will generally be a greater likelihood that a vehicle is travelling along a major road than a minor road where both of these cross the timing advance boundary under consideration and would have been available for use by the vehicle.
As noted hereinbefore, the particular positioning technology used to obtain the geographical positional data used in the present invention does not significantly affect the mode of operation of the invention. For the purposes of ease of illustration and understanding, the principal data processing steps will now be described in more detail with reference to one preferred form of the invention wherein is used the CGI+TA positioning method in which the geographical areas defined by the captured geographical positional data correspond to individual timing advance zones of individual (transmitter/receiver) base stations. (In fact as explained elsewhere herein, in the first instance there is captured proto-geographical positioning data comprising the base station and timing advance zone identities which are then intersected with base station and timing advance zone mapping data so as to provide the geographical area coordinates constituting the geographical positional data). It will be appreciated that in the case of other positioning technologies, the timing advance zones used in this particular case (using CGI+TA) will be replaced by the geographical areas as defined by the geographical (or proto-geographical) positioning data captured for the active MS device. In the case of the PCS (Personal Communications System) mobile phone networks widely used in the USA, timing advance zones are not used and the basic geographical positioning information used in the system is simply the identity of the cell within which the MS is located at the time (i.e. the positioning technology effectively is CGI without TA). Although the positional information with this system is generally less precise, it can nevertheless be quite practicable for major highways where the cells are relatively small (e.g. around 4000 meters across and smaller) which is in fact often the case with freeways in urban and suburban areas, which are precisely the areas where delays are more likely and where there is a greater demand for traffic delay reports. Of course where such (PCS and other non GSM) networks are provided with dedicated positioning technologies such as UL-TOA, E-OTD, or A-GPS, then these would normally be used to capture the geographical positional data.
The generation of the probability vector representing the likelihood of the vehicle having arrived at a position on a given one of the possible road components for all of the possible road components may be effected using any suitable criteria. Generally these will include the classification of the road and desirably also the length of the road within the timing advance zone, of which road the possible road component forms a part (where the road component is restricted to part of an individual road). The length of the road within the timing advance zone may be obtained from an intersection of the timing advance zone mapping data with the road network mapping data. As used herein the terms xe2x80x9cintersectionxe2x80x9d, xe2x80x9cintersectingxe2x80x9d etc. indicate any suitable process or procedure by means of which one type of data is compared with another type of data in order to determine the correlation therebetween. Thus for example a comparison of the geographical co-ordinates of a given timing advance zone may be compared with geographical co-ordinates of various road components in the network in order to determine which road components fall within or at least partially overlap that timing advance zone. The weighting assigned to different classifications of road is essentially arbitrary but could typically be as follows: motorway or freeway=10, major road or highway=8, and minor road or country road=2. The probability for the vehicle being on each one of the available roads is then determined by the product of the selected criteria, e.g. length of road xc3x97classification weighting.
Using the CGI+TA positioning system, the geographical positional data is generally captured when the device crosses a timing advance zone boundary between one timing advance zone and a neighbouring timing advance zone. Thus the system initially generates a probability vector when a vehicle carrying an active MS device crosses a first timing advance zone to a second timing advance zone. When the vehicle (MS device) crosses a second timing advance boundary from the second timing advance zone into a third timing advance zone, the system constructs a transition matrix representing all possible routes that could have been taken to get from the first timing advance boundary to the secondtiming advance boundary. For each route a probability is calculated as before. In addition an expected transit time is calculated based on the length of the road from the first timing advance boundary to the second one and the standard speed of the road classification concerned (modified if required by any special speed limit applicable). The actual transit time between the crossings of the first and second timing advance boundaries, may then be compared with the calculated expected transit times to provide an additional probability factor based on the fact that it is significantly less likely that the actual transit time will be substantially less rather than substantially more than the calculated expected transit time. This additional probability factor may then be applied to the transition matrix to produce a time dependent transition matrix, which can in turn be applied to the original probability vector to provide an updated probability vector representing the likelihood of the vehicle having arrived at a position on a given one of the said new possible road components. Thus, for example, where one (or more) of the originally available routes is absent from the time dependent matrix, then this can now be excluded from the updated probability vector. In addition it can also be excluded from the original (or previously updated) probability vector(s) thereby providing a more accurate historical record of the immediately preceding positions.
The information collected on the progress of the vehicle, in terms of its routing as provided by the updated probability vectors and its rate of progress as represented by its actual transit times, can now be combined with that for the other vehicles found to be using the same road component, to provide an average speed for that road component immediately before the latest average speed determination (typically within a time frame of less than a minute). Advantageously the average is skewed to provide increased weighting for faster moving vehicles as these will be more representative of the maximum available rate of progress on that roadxe2x80x94and hence the degree of congestion thereof, at the time. The degree of congestion is determined by comparing the calculated average with a normal (uncongested condition) average speed, to provide a delay factor indicating the degree of congestion on any convenient scale, such as a numerical or percentage scale.
It may be noted that how up-to-date the average speed determinations and delay factor reports are, will depend on the frequency with which geographical positioning data can be captured, which in turn will depend on the positioning system used. Thus, for example, where the CGI+TA positioning system is used, geographical positioning data is captured when a vehicle carrying an MS device crosses timing advance zone boundaries. Accordingly the greater the separation between these and the slower the vehicle speed, the longer the interval between the capture of the geographical positioning data, and in practice such intervals can typically range from less than one minute to several minutes or more. With other positioning system, such as, for example, A-GPS, geographical positioning data may be capturable rather more frequently and/or more regularly, for example, at a fixed interval in the range from 5 to 30 seconds. As noted elsewhere herein, average speed (or transit time etc) determinations are generally carried out for all vehicles which have passed along a road component of interest during a period of some minutes immediately before the determination, with suitable ageing (as further discussed hereinbelow) of increasingly older data used in the determination, and such determinations may be repeated at any convenient interval for example, from 1 second to 1 minute. (Alternatively, the system could be formed and arranged so that determinations are only carried out on-demand, as and when a user actually interrogated the system for particular road delay factor information). How up-to-date the reports received by the user are, may thus be a function of a number of factors such as the manner and frequency of generation of reports and the positioning system used.
It will of course be appreciated that the transit times and road delay factors may be utilised and/or presented in various different forms. Thus, for example, the transit times may be used directly or they could be used indirectly by being converted into speeds by dividing the distance travelled between the first and second road positions by the transit time xcex94t. The delay factors can be determined by comparing actual transit times with expected transit times, or could be determined by comparing actual speeds with expected speeds. The delay factor may be presented to the end user in various different ways which may be qualitative and/or quantitative. Thus, they could simply be presented descriptively and/or graphically, for example, by colour coding roads suitably in a visual display of the road networkxe2x80x94with green for no significant delays, amber for moderate delay, and red for serious delay, each level corresponding to a particular range of delay factors. Where the delay factors are presented quantitatively these could be in the form of numerical or graphical (e.g. bar) representations of a percentage speed reduction, a time delay, or any other convenient form.
Where it is desired to provide an indication of congestion in terms of an estimated delay time, then this could be indicated by the product of the difference between the calculated average speed and the normal average speed, and the total length of the road (possibly several successive road components) affected by the congestion. In practice, though, given that the system works primarily on transit times, it would usually be more convenient to derive estimated delay times based on comparisons of actual and estimated transit times.
By counting all the vehicles found to be using a particular road component, it is also possible to estimate the volume of traffic on the road (based on a typical proportion of vehicles carrying an active MS device using the mobile telecommunications device network at a given time). This information can then be used, if desired, optionally with other additional information such as time of day or night, weather conditions etc, in order to further refine the calculations used in the method of the invention. Thus, for example, the composition of the traffic in the middle of the night is likely to have a higher proportion of heavy goods vehicles (which are subject to lower speed limits than other vehicles) than during the day, which would result in the calculated average speed being biased downwardly. Accordingly the expected average speed used for comparison purposes at such times could be adjusted. Alternatively the expected average speed could be kept unchanged, and the weightings used in the calculation of the average speed at such times could be modified.
Most of the time for most road components there will be no significant congestion or delay factor present and therefore no particular interest in the calculated delay factors. Advantageously therefore the system of the present invention includes an algorithm for continuously monitoring the calculated delay factors for the presence of any which are greater than a predetermined threshold resulting in a delay of greater than say 10 minutes and selectively producing only reports for the roads concerned. The reports may be made available in a generally known manner through any suitable interface, including synthetic voice reports, graphical representations, conveniently superimposed on road map graphics, for display on suitable MS device display screens, text reports for transmission via SMS (Short Message Service), HTML (HyperText Mmarkup Language) and WML (Wireless Markup Language) format reports for uploading onto HTTP (HyperText Transport Protocol) and WAP (Wireless Application Protocol) servers for accessing via the Internet and over the air, cell broadcast message format for transmission via CB (Cell Broadcast) Centres, etc.
In order to enable the retrieval of reports of interest to the user, the user interface is generally provided with a query interface for interrogating the current road delay factor status database. In general, the query interface would be formed and arranged for enabling the user to request one or more of: delay by geographical area, delay by road number, and delay by place name e.g. town or village name. The query interface could, moreover be automated to a greater or lesser degreexe2x80x94for example, in the case of MS device within a given base station cell, the query interface could be formed and arranged to detect the cell identity (and hence geographical area) of that cell and then automatically generate suitable delay reports for roads within or crossing through that cell.
In general road traffic networks are represented in geographical data files as a series of road segments connected to each other at nodes which represent road junctions. The road segments are often rectilinear (to simplify and reduce the volume of data required). In the case of relatively long road segments corresponding to substantially non-rectilinear roads, then these may be broken up be using one or more pseudo-nodes between the actual nodes in order to enable the geographical data file representation of that road to follow more closely the actual geographical position of the road. Even so, the distance between neighboring nodes or pseudo-nodes may still be too great (especially in the case of motorways or freeways, or other major highways in open country) and in such cases it will generally be desirable for the purposes of the present invention to break up the road segments into shorter lengths allowing more accurate processing and monitoring of vehicle position and speed data. Given the typical speeds of vehicles in the road network and the levels of accuracy typically required for traffic delay or congestion reports, there is no particular advantage in making the road length units used in the method of the invention too small, and in general a suitable maximum length would be in the range from 200 m to 2000 m, preferably from 300 m to 1000 m, for example about 500 m, for the road segments used as road components in the methods and apparatus of the invention. Thus, for example, if a road segment in the geographic data file was greater than 500 m, then the data would be modified by breaking that segment up into shorter units, each of not more than 500 m length.
Conversely in the case of urban and sub-urban areas with relatively dense road networks, in which many of the roads are not significant xe2x80x9cthrough routesxe2x80x9d, there will be very large numbers of very short road segments. In order to simplify and reduce the processing load it may be desirable in such cases to treat several road segments as part of a single unit for processing purposes. Advantageously in the present invention there is used a geographical data file in which the road network data is modified so as to represent the roads in the form of units or xe2x80x9croad componentsxe2x80x9d of a length and or extent suitable for use in the method of the invention. Thus in the context of the present invention, a xe2x80x9croad componentxe2x80x9d may be any one of an actual length of road joining two junctions, part of such a length of road, and a group of interconnected roads.
It should be further noted that in the case of freeways and other major highways with two (or more) separate carriageways, each of these carriageways is normally represented as a separate road segment and thus would automatically be treated as separate road components, whilst in the case of single carriageway roads these are normally represented as single road segments. In order to be able to monitor differences in traffic flows in each direction along bi-directional single carriageway roads, it is therefore necessary to. modify the geographic data files used so as to provide duplicate road segment unitsxe2x80x94one for each directionxe2x80x94for use as the road components in the methods and apparatus of the invention.
For the avoidance of doubt references herein to xe2x80x9cpossiblexe2x80x9d road components are used to indicate all road components the geographical co-ordinates of whose extent fall within or overlap the geographical co-ordinates defining the extent of the geographical area defined by the geographical positional data which has been provided by the positioning system, i.e. all road components having geographical co-ordinates consistent or compatible with those of the geographical positional data. xe2x80x9cOriginalxe2x80x9d possible road components are such possible road components which have been identified for a first (or immediately preceding) captured geographical positional data, and xe2x80x9cnewxe2x80x9d possible road components are those identified for a second or newly captured geographical data.
In addition to providing a continuous reporting service, the system of the present invention can also be programmed to search the database for road delay factors above a predetermined threshold and outputting general alerts to broadcast type interfaces such as radio stations, web sites etc.
In another aspect the present invention provides a road traffic network congestion reporting system suitable for use in conjunction with a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positional data transmitting system, for monitoring and reporting on road traffic delays affecting the movement of vehicles through the road network, said reporting system comprising:
a storage device, and
a processor connected to said storage device; and
the storage device storing:
i) road network data representing the geographical position of road components making up said road network;
ii)expected vehicle speed data for individual parts of said road network; and
iii) a program for controlling the processor;
said processor operative with the program to:
It will be understood that the physical location and/or configuration of the computer system used in the present invention may have various different forms. Thus it may be substantially remote from the call management system and connected thereto in a WAN (Wide Area Network) or simply by any suitable telecommunications channel. Alternatively the apparatus could be coupled to the call management system through a LAN (Local Area Network), or even substantially integrated with the call management system computer.
In a further aspect the present invention provides a computer program product comprising:
a computer usable medium having computer readable code means embedded in said medium, said computer readable code means comprising a report generator for monitoring vehicular traffic flow in a road network and providing reports on congestion on individual roads in said road network, said report generator comprising executable program code for execution by a computer coupled with a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system providing positional data in respect of at least active mobile telecommunications devices belonging to said mobile telecommunications device network, wherein said executable program code:
a. captures geographical positional data for an MS mobile telecommunications device;
b. intersects said geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify possible road components corresponding to said geographical positional data;
c. generates a probability vector representing the likelihood of said vehicle having arrived at a position on any of said possible road components;
d. identifies available routes in the road network linking said possible road components corresponding to a given geographical positional data and a preceding possible road components corresponding to a preceding geographical positional data, which routes are constituted by a series of road components;
e. intersects said available routes with expected average vehicle speed data for the road components of said series of road components constituting said available routes so as to determine expected transit times for said available routes;
f. directly or indirectly compares the actual transit time with the expected transit time for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time; and
g. determines an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of a given available route having been followed.